To solve this problem, there's an intermediate class that imports the correct set of methods. This class then inherits from the intermediate class. This works, and isolates the tricky bits to a single intermediate class, but it also demonstrates the problems that can crop up when multiple inheritance is combined with a strong aversion to code duplication.

Inheritence shenanigans aside, this class is a good example of a compound field that also provides an "inflated" internal value (a DateTime object).